Small Diameter, High Strength, Low Elongation, Creep Resistant, Abrasion Resistant Braided Structure

ABSTRACT

A braided structure that includes a core and a sheath is provided. The core includes a yarn formed at least in part from an aromatic polymer (e.g., an aromatic polyester/liquid crystalline polymer or an aramid polymer), and the sheath, which includes a plurality of ultra high molecular weight polyolefin yarns, is braided around the core. The sheath has an overall diameter ranging from about 60 micrometers to about 650 micrometers. Despite its small diameter, the braided structure can be creep resistant and abrasion resistant while at the same time exhibiting low elongation, a high load at break, and high stiffness. The braided structure can be used in medical applications such as sutures, load bearing orthopedic applications, artificial tendons/ligaments, fixation devices, actuation cables, components for tissue repair, etc.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 62/649,906 having a filing date of Mar. 29, 2018, theentire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to a braided structure, and,more particularly, to a small diameter braided structure that is creepresistant and abrasion resistant while at the same time having highstrength and low elongation.

BACKGROUND OF THE INVENTION

Braided structures are often used in the medical field for sutures, loadbearing orthopedic applications, artificial tendons/ligaments, devicefixation, actuation cables, tissue repair, etc. Because of the smalldiameter required for many applications, other properties of the braidedstructure are compromised. For example, while it may be possible todevelop a braided structure with a small diameter (e.g., less than 1millimeter, such as less than about 500 micrometers), there have beendifficulties in designing such a structure to also be creep resistantand/or abrasion resistant. Challenges have also arisen in developing abraided structure having a small diameter that also has low elongationand high strength.

As such, a need exists for a braided structure having a small diametersuch that it is suitable for use in medical applications while at thesame time having the desired mechanical properties (e.g., creepresistance, abrasion resistance, low elongation, and/or high strength).

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one aspect, the present invention is directed to a braided structurethat includes a core composed of a yarn, wherein the yarn includes anaromatic polymer; and a sheath braided around the core, wherein thesheath includes a plurality of ultra high molecular weight polyolefinyarns. Further, the braided structure has an overall diameter rangingfrom about 60 micrometers to about 650 micrometers.

In one particular embodiment, the aromatic polymer can include a liquidcrystalline polymer, an aramid polymer, or a combination thereof.

In still another aspect, the sheath can include from 2 yarns to about 48yarns or carriers and each of the plurality of yarns or carriers in thesheath can include from 1 filament to about 72 filaments.

In yet another aspect, the sheath can include at least two sheathlayers.

In one more aspect, the yarn can include from about 3 filaments to about96 filaments.

In an additional aspect, the core can include a single yarn or at leastone yarn. Further, when the core includes a single yarn, it is to beunderstood that the core can include at least one additional yarn (e.g.,the single yarn can be 2-ply where the yarn acts as a single yarn).

In one aspect, the core can have a first diameter and the sheath canhave a second diameter, where the ratio of the first diameter to thesecond diameter ranges from about 1:12 to about 7:10.

In still another aspect, the ultra high molecular weight polyolefin caninclude an ultrahigh molecular weight polyethylene (UHMWPE) having aweight average molecular weight (Mw) of at least about 500,000grams/mole (g/mol).

In yet another aspect, the braided structure can exhibit a creep of lessthan about 0.60 inches (about 15.2 millimeters) when subjected to aconstant load of 5 pounds-force (about 22.2 Newtons) for about 15minutes at an about 19 inch (48.3 centimeter) gage length on a horngrip. In another aspect, the braided structure can exhibit a creep ofless than about 8 percent elongation after about 15 minutes.

In one more aspect, the braided structure can exhibit resistance toabrasion after cycling the braided structure 20 millimeters in abackwards direction and 20 millimeters in a forwards direction for atotal of 40 cycles across a metal edge having a 1 millimeter radius with200 grams of weight applied to the braided structure, wherein thebraided structure includes less than 50 broken filaments per linear inchafter cycling.

In an additional aspect, the braided structure can exhibit a load atbreak ranging from about 5 pounds-force (about 22.2 Newtons) to about 60pounds-force (about 266.9 Newtons).

In one aspect, the braided structure can exhibit an extension at breakranging from about 2% to about 5.5%.

In another aspect, the braided structure can exhibit a stiffness rangingfrom about 10 pounds-force per inch (about 1.75 Newtons/millimeter) toabout 90 pounds-force per inch (about 15.8 Newtons/millimeter).

In an additional aspect, the braided structure can exhibit an ultimatetensile strength ranging from about 8.0×10⁴ pounds per square inch(about 550 megapascals) to about 3.9×10⁵ pounds per square inch (about2710 megapascals). In another aspect, the braided structure can exhibitan ultimate tensile strength ranging from about 15 grams/denier yarn toabout 35 grams/denier yarn.

In still another aspect, the braided structure can include from about 10picks per inch (PPI) to about 90 picks per inch (PPI).

In yet another aspect, the sheath yarn can include from about 0 twistsper inch (TPI) to about 12 twists per inch (TPI).

In one more aspect, the core yarn can include zero twists per inch (TPI)to about two TPI.

In an additional aspect, each of the plurality of yarns in the sheathcan have a linear mass density ranging from about 8 denier to about 125denier.

In one more aspect, the yarn in the core can have a linear mass densityranging from about 8 denier to about 1110 denier.

In another aspect, the present invention is directed to a medicaldevice, a suture, a load bearing orthopedic application, an artificialtendon, an actuation cable, a component for tissue repair, or a fixationdevice that includes a braided structure as set forth above.

In still another aspect, the present invention is directed to a braidedstructure composed of a core that includes a yarn, where the yarnincludes an aromatic polymer and a sheath braided around the core, wherethe sheath includes a plurality of ultra high molecular weightpolyolefin yarns. Further, the braided structure exhibits an ultimatetensile strength ranging from about 8.0×10⁴ pounds per square inch(about 550 megapascals) to about 3.9×10⁵ pounds per square inch (about2710 megapascals). In another aspect, the braided structure can exhibitan ultimate tensile strength ranging from about 15 grams/denier yarn toabout 35 grams/denier yarn.

In yet another aspect, the present invention is directed to a braidedstructure composed of a core that includes a yarn, where the yarnincludes an aromatic polymer and a sheath braided around the core, wherethe sheath includes a plurality of ultra-high molecular weightpolyolefin yarns. Further, the braided structure exhibits a creep ofless than about 0.60 inches (about 15.2 millimeters) when subjected to aconstant load of 5 pounds-force (about 22.2 Newtons) for about 15minutes and at an about 19 inch (48.3 centimeter) gage length on a horngrip. In another aspect, the braided structure exhibits a creep of lessthan about 8% elongation after about 15 minutes.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 illustrates a side view of a braided structure contemplated bythe present invention;

FIG. 2 illustrates a cross-sectional view of the braided structure ofFIG. 1 taken at line C-C;

FIG. 3 is a photograph of a comparative example braided structure havinga liquid crystalline polymer sheath after 5 abrasion testing cycles;

FIG. 4 is a photograph of a comparative example braided structure havinga liquid crystalline polymer sheath after 10 abrasion testing cycles;

FIG. 5 is a photograph of a comparative example braided structure havinga liquid crystalline polymer sheath after 20 abrasion testing cycles;

FIG. 6 is a photograph of a comparative example braided structure havinga liquid crystalline polymer sheath after 40 abrasion testing cycles;

FIG. 7 is a photograph of a braided structure of the present inventionhaving an ultra-high molecular weight polyethylene polymer sheath after5 abrasion testing cycles;

FIG. 8 is a photograph of a braided structure of the present inventionhaving an ultra-high molecular weight polyethylene polymer sheath after10 abrasion testing cycles;

FIG. 9 is a photograph of a braided structure of the present inventionhaving an ultra-high molecular weight polyethylene polymer sheath after20 abrasion testing cycles; and

FIG. 10 is a photograph of a braided structure of the present inventionhaving an ultra-high molecular weight polyethylene polymer sheath after40 abrasion testing cycles.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Generally speaking, the present invention is directed to a braidedstructure that includes a core and a sheath. The core includes a yarnformed from an aromatic polymer (e.g., a liquid crystalline polymer, anaramid polymer, or a combination thereof), and the sheath, whichincludes a plurality of ultra-high molecular weight polyolefin yarns, isbraided around the core. In some embodiments, the core can be a singleyarn, although in other embodiments, it is to be understood that thecore can include more than one yarn. The sheath has an overall diameterranging from about 60 micrometers to about 650 micrometers. Despite itssmall diameter, the braided structure can be creep resistant andabrasion resistant while at the same time exhibiting low elongation, ahigh load at break, and high stiffness. The braided structure can beused in medical applications such as sutures, load bearing orthopedicapplications, artificial tendons/ligaments, device fixation, actuationcables for medical devices, components for tissue repair, etc.

Referring now to the drawings, FIG. 1 illustrates a side view of abraided structure 100 contemplated by the present invention, while FIG.2 illustrates a cross-sectional view of the braided structure 100 takenat line C-C. The braided structure 100 includes a core 102 surrounded bya sheath 104 and is braided in a 1×1 pattern. However, other braidpatterns known in the art can alternatively be used (e.g., 1×2, 2×2,etc.). The core 102 can include a single strand of yarn, where the yarncan include from about 3 filaments to about 96 filaments, such as fromabout 4 filaments to about 84 filaments, such as from about 5 filamentsto about 72 filaments, such as from about 6 filaments to about 60filaments. In one particular embodiment as shown in FIGS. 1 and 2, thecore 102 can include a single yarn. However, it is also to be understoodthat the core 102 can include more than a single yarn, such as at leastone additional yarn, such that the core 102 can include from about 2yarns to about 10 yarns, such as from about 2 yarns to about 8 yarns,such as from about 2 yarns to about 6 yarns, such as from about 4 yarnsto about 8 yarns, such as from about 4 yarns to about 6 yarns, where theyarns can be braided or unbraided. The sheath 104 can include from 2yarns to about 48 yarns, such as from 3 yarns to about 24 yarns, such asfrom about 4 yarns to about 16 yarns.

It is also to be understood that the sheath yarns and/or core yarns maycontain twist or no twist or no intentional twist or unintentionaltwist. Yarn twist can include from 0 to 2 intentional or unintentionaltwists per inch, such as from 0 to 1 intentional or unintentional twistsper inch, such as from 0 to 0.75 intentional or unintentional twists perinch, such as from 0 to 0.5 intentional or unintentional twists perinch, such as from 0 to 0.25 intentional or unintentional twists perinch. It is to be understood that unintentional twist may include twistthat accumulates in the yarn during normal manufacturing processes. Anon-limiting example of unintentional twist is twist that is obtainedonce the yarn is wrapped or spun on the spool.

Meanwhile, the sheath 104 can include a plurality of S yarns 106 or Zyarns 108 wrapped around the core 102. During manufacturing of a braidedstructure, a portion of the machine yarn carriers can move in aclockwise direction, and the other portion of the carriers can move in acounter-clockwise direction. In a non-limiting example, half of thecarriers move in the clockwise direction and the other half of thecarriers move in the counter-clockwise direction. As the machinecarriers move around the braided structure, yarn is pulled off eachcarrier and gathered at the braiding point. The sheath yarn may benaturally twisted or unintentionally twisted due to the movement of thecarriers around the machine. For optimal braid strength and minimalbraid creep, the yarn filaments must remain close to parallel with thebraided structure by using sheath yarn with S twist moving clockwisedirection around the braided structure and sheath yarn with Z twistmoving counter-clockwise direction around the braided structure.

In other words, the sheath yarn 104 can exhibit twist in both the S andZ directions. For instance, the sheath yarn 104 can include from 1 toabout 12, such as from about 2 to about 10, such as from about 3 toabout 8 S or Z yarns braided clockwise 106 and from 1 to about 12, suchas from about 2 to about 10, such as from about 3 to about 8 opposing Sor Z yarns braided counterclockwise 108. In other words, the sheath caninclude from 2 yarns to about 48 yarns, such as from about 4 yarns toabout 24 yarns, such as from about 6 yarns to about 16 yarns, where halfof the yarns are wrapped around the core in a clockwise direction andhalf of the yarns are wrapped around the core in a counterclockwisedirection.

In one particular embodiment as shown in FIG. 2, the sheath 104 caninclude three S or Z yarns 110, 114, and 118 and three opposing S or Zyarns 112, 116, and 120. Moreover, each clockwise carrier of S, Z, oruntwisted yarn 106 or counterclockwise carrier of S, Z, or untwistedyarn 108 can include from 1 filament to about 72 filaments, such as from2 filaments to about 60 filaments, such as from about 4 filaments toabout 48 filaments, such as from about 6 filaments to about 36filaments. The overall stiffness and flexibility of the braidedstructure 100 can be optimized based on the number of yarn filaments. Inone embodiment, increasing the number of yarn filaments can improve theabrasion resistance of the braided structure 100.

Further, the braided structure 100 can have an overall diameter D1ranging from about 0.0024 inches to about 0.026 inches (about 60micrometers to about 650 micrometers), such as from about 0.0057 inchesto about 0.026 inches (about 145 micrometers to about 650 micrometers),such as from about 0.0085 inches to about 0.025 inches (about 215micrometers to about 625 micrometers), such as from about 0.009 inchesto about 0.024 inches (about 230 micrometers to about 600 micrometers),such as from about 0.0095 inches to about 0.023 inches (about 245micrometers to about 575 micrometers), such as from about 0.0118 inchesto about 0.016 inches (about 300 micrometers to about 400 micrometers).Meanwhile, the core 102 can have a diameter D2 ranging from about 0.0012inches to about 0.031 inches (about 30 micrometers to about 333micrometers), such as from about 0.0014 inches to about 0.0046 inches(about 36 micrometers to about 116 micrometers), such as from about0.0016 inches to about 0.0044 inches (about 40 micrometers to about 112micrometers), such as from about 0.0018 inches to about 0.0042 inches(about 46 micrometers to about 108 micrometers), while each of theindividual sheath yarns 110, 112, 114, 116, 118, and 120 can have adiameter D3 ranging from about 0.0013 inches to about 0.0060 inches(about 30 micrometers to about 152 micrometers), such as from about0.0026 inches to about 0.0058 inches (about 66 micrometers to about 148micrometers), such as from about 0.0024 inches to about 0.0056 inches(about 60 micrometers to about 142 micrometers), such as from about0.0030 inches to about 0.0054 inches (about 76 micrometers to about 138micrometers).

In one particular embodiment, the ratio of the diameter D2 of the core102 to the diameters D3 of each of the yarns in 110, 112, 114, 116, 118,and 120 in the sheath 104 (D2:D3) can range from about 1:12 to about7:10, such as from about 1:8 to about 2:3, such as from 1:4 to about1:2, such as from 1:3 to about 4:10. Without intending to be limited byany particular theory, the present inventors have found that such abalance between the diameter D2 of the core 102 and the diameter D3 ofeach of the yarns in the sheath 104, in conjunction with othercharacteristics such as the materials used for the core 102 and thesheath 104, results in a braided structure 100 that has a small diametersuch that it can be used as a suture or other medical application (e.g.,actuation cables) without sacrificing the mechanical properties of thebraided structure (e.g., creep resistance, abrasion resistance, lowelongation, high strength, etc.).

In applications where a braided structure is used with, within, or inconjunction with a medical device, the material properties andmechanical properties of the core 102 and sheath 104 effect the braidedstructure and the overall device containing the braided structure. Inone embodiment, by utilizing the balance of diameter D2 of the core 102and the diameter D3 of the sheath 104, the preferred overall diameter ofthe braided structure 100 can be achieved to fit through a smalldesignated lumen within a medical device and still met the requirementsfor adequate strength and creep resistance. Furthermore, a braidedstructure 100 containing a core 102 and sheath 104 larger than thepreferred diameter range of the present invention would not fit within adesignated lumen for specific medical device applications. Additionally,braided structures with tensile strength higher than the preferred rangeof the present invention may result in damage to the final medicaldevice that contains a braided structure 100. Moreover, to protect thecore 102 from abrasion and yarn misalignment, the diameter D2 of thecore 102 and diameter D3 of the sheath 104 are selected to provideadequate sheath coverage around the core 102 with a desired picks perinch.

Moreover, the linear mass density of the core 102 and sheath 104 canalso be controlled to obtain the desired properties of the braidedstructure. Specifically, the linear mass density of the core 102 canrange from about 8 denier to about 1110 denier, such as from about 75denier to about 125 denier, such as from about 80 denier to about 120denier. Further, the linear mass density of each of the yarns in thesheath 104 can range from about 8 denier to about 125 denier, such asfrom about 25 denier to about 75 denier, such as from about 30 denier toabout 70 denier, such that the overall linear mass density of the sheath104 can also range from about 8 denier to about 125 denier, such as fromabout 25 denier to about 75denier, such as from about 30 denier to about70 denier.

Moreover, although in some embodiments the core 102 comprises a singleyarn have 0 twist per inch, when a single or plurality of yarns areutilized, the core yarn 102 can have from 0 twist per inch (TPI) toabout 1 TPI, such as from 0 TPI to about 2 TPI, such as from 0 TPI toabout 15 TPI, such as from about 4 TPI to about 10 TPI, such as fromabout 5 TPI to about 9 TPI. In addition, the sheath yarn 104 can beformed so that it includes from 0 twist per inch (TPI) to about 1 TPI,such as from 0 TPI to about 2 TPI, such as from 0 TPI to about 15 TPI, 3TPI to about 12 TPI, such as from about 4 TPI to about 10 TPI, such asfrom about 5 TPI to about 9 TPI. The TPI of the braided structureeffects the abrasion resistance of the braided structure 100, whereabrasion during manufacturing of the braided structure can be minimizedwithout compromising the tensile strength by using the preferred TPIrange of the disclosed invention. Twists may include unintentional twistobtained once the yarn is wrapped or spun on the spool or intentionaltwist incorporated into the yarn by a manufacturing process.

Further, the braided structure 100 can include from about 10 picks perinch (PPI) to about 90 picks per inch, such as from about 12 PPI toabout 60 PPI, such as from about 14 PPI to about 40 PPI. By using thepreferred PPI range, low creep, low elongation, and desired stiffness ofthe braided structure can be achieved. For example, a PPI greater thanthe preferred range can result in an undesired high creep andelongation, which, in turn, decreases the stiffness of the braidedstructure outside of the desired stiffness range. Moreover, utilizing aPPI lower than the preferred range can result in an undesired low creepand elongation, which, in turn, increases the stiffness of the braidedstructure outside of the desired stiffness range. Further, while a PPIvalue lower than the preferred range may result in a braided structurewith minimal creep, this low PPI value may not provide adequate sheathyarn coverage around the core, which may result in poor abrasionresistance.

Based on the specific combination of sheath and core yarncharacteristics described above, a small diameter braided structurehaving a diameter ranging from about 60 micrometers to about 650micrometers can be formed that exhibits desired abrasion resistance,creep resistance, load at break, load at break with 180° bend, extensionat break, and stiffness.

For instance, the braided structure 100 of the present invention can beabrasion resistant in that it exhibits little to no fraying. In oneembodiment, the braided structure includes less than 50 broken filamentsper linear inch, such as less than 25 broken filaments per linear inch,such less than 10 broken filaments per linear inch, such as less than 5broken filaments per linear inch after cycling the braided structure 20millimeters in a backwards direction and 20 millimeters in a forwardsdirection for a total of 40 cycles across a metal edge having a 1millimeter radius with 200 grams of weight applied to the braidedstructure.

Further, the braided structure 100 of the present invention can exhibita creep of less than about 0.60 inches (about 15.2 millimeters), such asless than about 0.58 inches (about 14.7 millimeters), such as less thanabout 0.56 inches (about 14.2 millimeters), such as less than about 0.54millimeters (about 13.7 millimeters) when subjected to a constant loadof 5 pounds-force (about 22.2 Newtons) for about 15 minutes and at anabout 19 inch (48.3 centimeter) gage length on a horn grip. In oneparticular embodiment, the creep can range from about 0.001 inches(about 0.0025 millimeters) to about 0.25 inches (about 6.4 millimeters).

Further, the braided structure 100 of the present invention can exhibita creep of less than about 8% elongation after about 15 minutes, such asless than about 7% elongation after about 15 minutes, such as less thanabout 6% elongation after about 15 minutes, such as less than about 4%elongation after about 15 minutes, such as less than about 3% elongationafter about 15 minutes, such as less than about 2% elongation afterabout 15 minutes, such as less than about 1% elongation after about 15minutes, such as less than about 0.5% elongation after about 15 minutes,such as less than about 0.25% elongation after about 15 minutes. In oneembodiment, the braided structure 100 can exhibit a creep between about0.2% and about 3% elongation after about 15 minutes.

In addition, when undergoing tensile testing, the braided structure 100of the present invention can exhibit a load at break ranging from about5 pounds-force (about 22.2 Newtons) to about 60 pounds-force (about266.9 Newtons), such as from about 7.5 pounds-force (about 33.4 Newtons)to about 50 pounds-force (about 222.4 Newtons), such as from about 10pounds-force (about 44.5 Newtons) to about 40 pounds-force (about 177.9Newtons), such as from about 12.5 pounds-force (about 55.6 Newtons) toabout 30 pounds-force (about 133.4 Newtons).

Further, when subjected to tensile testing, the braided structure 100 ofthe present invention can exhibit a load at break with an 180° bendranging from about 10 pounds-force (about 44.5 Newtons) to about 70pounds force (about 311.4 Newtons), such as from about 12.5 pounds-force(about 55.6 Newtons) to about 60 pounds-force (about 266.9 Newtons),such as from about 15 pounds-force (about 66.7 Newtons) to about 50pounds-force (about 222.4 Newtons) when the braided structure is wrappedaround a pin or wire having a diameter ranging from about 0.009 inches(about 229 micrometers) to about 0.015 inches (about 381 micrometers),such as about 0.012 inches (about 305 micrometers).

Moreover, when subjected to tensile testing, the braided structure 100of the present invention can exhibit an extension or elongation at breakranging from about 2% to about 5.5%, such as from about 2.1% to about5%, such as from about 2.2% to about 4.75%, such as from about 2.3% toabout 4.5%.

Additionally, when subjected to tensile testing, the braided structure100 of the present invention can exhibit a stiffness ranging from about10 pounds-force/inch (about 1.75Newtons/millimeter) to about 90pounds-force/inch (about 15.8 Newtons/millimeter), such as from about 15pounds-force/inch (about 2.6 Newtons/millimeter) to about 85pounds-force/inch (about 14.9 Newtons/millimeter), such as from about 20pounds-force/inch (about 3.5 Newtons/millimeter) to about 80pounds-force/inch (about 14.0 Newtons/millimeter, such as from about 25pounds-force/inch (about 4.4 Newtons/millimeter) to about 75pounds-force/inch (about 13.1 Newtons/millimeter).

Further, when subjected to tensile testing, the braided structure canexhibit an ultimate tensile strength ranging from about 8.0×10⁴ poundsper square inch (about 550 megapascals) to about 3.9×10⁵ pounds persquare inch (about 2710 megapascals), such as from about 1.5×10⁵ poundsper square inch (about 1034 megapascals) to about 3×10⁵ pounds persquare inch (about 2068 megapascals), such as from about 1.6×10⁵ poundsper square inch (about 1103 megapascals) to about 2.75×10⁵ pounds persquare inch (about 1896 megapascals), such as from about 1.7×10⁵ poundsper square inch (about 1172 megapascals) to about 2.5×10⁵ pounds persquare inch (about 1723 megapascals).

In another aspect, the braided structure can exhibit an ultimate tensilestrength ranging from about 15 grams/denier yarn to about 35grams/denier yarn, such as to about 16 grams/denier yarn to about 30grams/denier yarn, such as to about 18 grams/denier yarn to about 25grams/denier yarn, such as to about 20 grams/denier yarn to about 25grams/denier yarn, such as to about 22 grams/denier yarn to about 25grams/denier yarn.

The various components of the braided structure will now be described inmore detail.

I. Core

According to the present invention, the core of the braided structurecan include a single aromatic polymer yarn. For instance, the aromaticpolymer can include a liquid crystalline polymer, an aramid polymer, ora combination thereof. The term “liquid crystalline polymer” or “LCP”refers to a polymer that can possess a rod-like structure that allows itto exhibit liquid crystalline behavior in its molten state (e.g.,thermotropic nematic state). The polymer may contain aromatic units(e.g., aromatic polyesters, aromatic polyesteramides, etc.) so that itis wholly aromatic (e.g., containing only aromatic units) or partiallyaromatic (e.g., containing aromatic units and other units, such ascycloaliphatic units). The polymer may also be fully crystalline orsemi-crystalline in nature. In some embodiments, suitable thermotropicliquid crystalline polymers may include, for instance, aromaticpolyesters (e.g., liquid crystalline aromatic polyesters or liquidcrystalline polyesters), aromatic poly(esteramides), aromaticpoly(estercarbonates), aromatic polyam ides, etc., and may likewisecontain repeating units formed from one or more aromatichydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols,aromatic aminocarboxylic acids, aromatic amines, aromatic diamines,etc., as well as combinations thereof.

Aromatic polyesters, for instance, may be obtained from (1) two or morearomatic hydroxycarboxylic acids; (2) at least one aromatichydroxycarboxylic acid, at least one aromatic dicarboxylic acid, and atleast one aromatic diol; and/or (3) at least one aromatic dicarboxylicacid and at least one aromatic diol. Examples of suitable aromatichydroxycarboxylic acids include, 4-hydroxybenzoic acid;4-hydroxy-4′-biphenylcarboxylic acid; 2-hydroxy-6-naphthoic acid;2-hydroxy-5-naphthoic acid; 3-hydroxy-2-naphthoic acid;2-hydroxy-3-naphthoic acid; 4′-hydroxyphenyl-4-benzoic acid;3′-hydroxyphenyl-4-benzoic acid; 4′-hydroxyphenyl-3-benzoic acid, etc.,as well as alkyl, alkoxy, aryl and halogen substituents thereof.Examples of suitable aromatic dicarboxylic acids include terephthalicacid; isophthalic acid; 2,6-naphthalenedicarboxylic acid; diphenylether-4,4′-dicarboxylic acid; 1,6-naphthalenedicarboxylic acid;2,7-naphthalenedicarboxylic acid; 4,4′-dicarboxybiphenyl;bis(4-carboxyphenyl)ether; bis(4-carboxyphenyl)butane;bis(4-carboxyphenyl)ethane; bis(3-carboxyphenyl)ether;bis(3-carboxyphenyl)ethane, etc., as well as alkyl, alkoxy, aryl andhalogen substituents thereof. Examples of suitable aromatic diolsinclude hydroquinone; resorcinol; 2,6-dihydroxynaphthalene;2,7-dihydroxynaphthalene; 1,6-dihydroxynaphthalene;4,4′-dihydroxybiphenyl; 3,3′-dihydroxybiphenyl; 3,4′-dihydroxybiphenyl;4,4′-dihydroxybiphenyl ether; bis(4-hydroxyphenyl)ethane, etc., as wellas alkyl, alkoxy, aryl and halogen substituents thereof. In oneparticular embodiment, the aromatic polyester is derived from4-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid. The monomer unitsderived from 4-hydroxybenzoic acid may constitute from about 45% toabout 85% (e.g., 73%) of the polymer on a mole basis and the monomerunits derived from 2,6-hydroxynaphthoic acid may constitute from about15% to about 55% (e.g., 27%) of the polymer on a mole basis. Thesynthesis and structure of these and other aromatic polyesters may bedescribed in more detail in U.S. Pat. Nos. 4,161,470; 4,473,682;4,522,974; 4,375,530; 4,318,841; 4,256,624; 4,219,461; 4,083,829;4,184,996; 4,279,803; 4,337,190; 4,355,134; 4,429,105; 4,393,191;4,421,908; 4,434,262; and 5,541,240.

Liquid crystalline polyesteramides may likewise be obtained from (1) atleast one aromatic hydroxycarboxylic acid and at least one aromaticaminocarboxylic acid; (2) at least one aromatic hydroxycarboxylic acid,at least one aromatic dicarboxylic acid, and at least one aromatic amineand/or diamine optionally having phenolic hydroxy groups; and (3) atleast one aromatic dicarboxylic acid and at least one aromatic amineand/or diamine optionally having phenolic hydroxy groups. Suitablearomatic amines and diamines may include, for instance, 3-aminophenol;4-aminophenol; 1,4-phenylenediamine; 1,3-phenylenediamine, etc., as wellas alkyl, alkoxy, aryl and halogen substituents thereof. In oneparticular embodiment, the aromatic polyesteramide is derived from2,6-hydroxynaphthoic acid, terephthalic acid, and 4-aminophenol. Themonomer units derived from 2,6-hydroxynaphthoic acid may constitute fromabout 35% to about 85% of the polymer on a mole basis (e.g., 60%), themonomer units derived from terephthalic acid may constitute from about5% to about 50% (e.g., 20%) of the polymer on a mole basis, and themonomer units derived from 4-aminophenol may constitute from about 5% toabout 50% (e.g., 20%) of the polymer on a mole basis. In anotherembodiment, the aromatic polyesteramide contains monomer units derivedfrom 2,6-hydroxynaphthoic acid, and 4-hydroxybenzoic acid, and4-aminophenol, as well as other optional monomers (e.g.,4,4′-dihydroxybiphenyl and/or terephthalic acid). The synthesis andstructure of these and other aromatic poly(esteram ides) may bedescribed in more detail in U.S. Pat. Nos. 4,339,375; 4,355,132;4,351,917; 4,330,457; 4,351,918; and 5,204,443.

Meanwhile, the term “aramid polymer” refers to a class of polymers knownas aromatic polyamides. Such polymers are typically prepared by thereaction between an amine group and a carboxylic acid halide group.Examples of suitable aramid polymers contemplated by the presentinvention include poly-metaphenylene isophthalam ides and p-phenyleneterephthalam ides.

In one particular embodiment, the aromatic polymer can be formed into acore 102 having a single yarn with zero turns per inch that has a linearmass density ranging from about 96 denier to about 105 denier. The yarncan also include from about 36 to about 72 filaments and can have adiameter ranging from about 0.0036 inches to about 0.0041 inches (about90 micrometers to about 105 micrometers). Further, the single yarn ofthe core 102 can exhibit a percent elongation (extension at break)ranging from about 2.1% to about 2.5%. In addition, the yarn can exhibita tenacity ranging from about 21 g/denier to about 28 g/denier and canhave a maximum force ranging from about 2016 grams to about 2940 grams.

In another particular embodiment, the aromatic polymer can be formedinto a core 102 having a single yarn with zero turns per inch that has alinear mass density ranging from about 21 denier to about 29 denier. Theyarn can also include from 2 to about 12 filaments and can have adiameter ranging from about 0.0018 inches to about 0.0022 inches (about46 micrometers to about 56 micrometers). Further, the single yarn of thecore 102 can exhibit a percent elongation (extension at break) rangingfrom about 3% to about 5%. In addition, the yarn can exhibit a tenacityranging from about 20 g/denier to about 40 g/denier and can have amaximum force ranging from about 600 grams to about 950 grams.

II. Sheath

According to the present invention, the sheath of the braided structurecan include a plurality of sheath yarns formed from a high molecularweight polymer, such as a high molecular weight polyolefin.

In one particular embodiment, the sheath can include a plurality ofsheath yarns formed from an ultra high molecular weight polyethylene(UHMWPE) polymer that can have a weight average molecular weight (Mw) ofat least about 500,000 grams/mole (g/mol). In some embodiments, theaverage molecular weight of the UHMWPE polymer can range from about500,000 g/mol to about 10,000,000 g/mol, such as from about 1,000,000g/mol to about 8,000,000 g/mol, such as from about 1,000,000 g/mol toabout 6,000,000 g/mol, such as from about 2,000,000 g/mol to about4,000,000 g/mol.

In addition, the UHMWPE polymer may be a homopolymer of ethylene or acopolymer of ethylene and at least one comonomer. Suitable comonomersthat may be used to form a UHMWPE copolymer include, but are not limitedto, an alpha-olefin or cyclic olefin having 3 to 20 carbon atoms.Non-limiting examples of suitable comonomers include 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, cyclohexene, and dienes withup to 20 carbon atoms (e.g. butadiene or 1,4-hexadiene). Comonomers maybe present in the UHMWPE copolymer in an amount from about 0.001 mole %to about 10 mole %, from about 0.01 mole % to about 5 mole %, or fromabout 0.1 mole % to about 1 mole %.

In one particular embodiment, the sheath 104 can include 6 UHMWPE yarnshaving between 6 and 7 turns per inch (TPI), where each yarn has alinear mass density ranging from about 40 denier to about 60 denier sothat the overall linear mass density of the sheath 104 also ranges fromabout 40 denier to about 60 denier. Each of the yarns in the sheath 104can also include from about 20 to about 35 filaments and can have adiameter ranging from about 0.0030 inches to about 0.0037 inches (about76 micrometers to about 94 micrometers). Further, each of the yarns inthe sheath 104 can exhibit a percent elongation (extension at break)ranging from about 1.3% to about 7%. In addition, each of the yarns canexhibit a tenacity ranging from about 25 g/denier to about 51 g/denierand can have a maximum force ranging from about 1150 grams to about 3036grams.

In one particular embodiment, the sheath 104 can include from 4 to 24UHMWPE untwisted yarns, where each yarn has a linear mass densityranging from about 40 denier to about 60 denier so that the overalllinear mass density of the sheath 104 also ranges from about 25 denierto about 120 denier. Each of the yarns in the sheath 104 can alsoinclude from about 16 to about 42 filaments and can have a diameterranging from about 0.0030 inches to about 0.0052 inches (about 76micrometers to about 132 micrometers). Further, each of the yarns in thesheath 104 can exhibit a percent elongation (extension at break) rangingfrom about 2% to about 5%. In addition, each of the yarns can exhibit atenacity ranging from about 20 g/denier to about 55 g/denier and canhave a maximum force ranging from about 650 grams to about 4500 grams.

In another embodiment, the yarns in the sheath 104 can include anotherpolymer in addition to a high molecular weight polyolefin. For instance,one or more of the yarns in the sheath 104 can include a blend of thehigh molecular weight polyolefin and an additional polymer, or one ormore of the yarns can be formed solely from the additional polymer. Inone embodiment, the additional polymer can be an aromatic polymer. Forinstance, the aromatic polymer can include a liquid crystalline polymer,an aramid polymer, or a combination thereof. The term “liquidcrystalline polymer” or “LCP” refers to a polymer that can possess arod-like structure that allows it to exhibit liquid crystalline behaviorin its molten state (e.g., thermotropic nematic state). The polymer maycontain aromatic units (e.g., aromatic polyesters, aromaticpolyesteramides, etc.) so that it is wholly aromatic (e.g., containingonly aromatic units) or partially aromatic (e.g., containing aromaticunits and other units, such as cycloaliphatic units). The polymer mayalso be fully crystalline or semi-crystalline in nature. In someembodiments, suitable thermotropic liquid crystalline polymers mayinclude, for instance, aromatic polyesters (e.g., liquid crystallinearomatic polyesters or liquid crystalline polyesters), aromaticpoly(esteramides), aromatic poly(estercarbonates), aromatic polyamides,etc., and may likewise contain repeating units formed from one or morearomatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromaticdiols, aromatic aminocarboxylic acids, aromatic amines, aromaticdiamines, etc., as well as combinations thereof.

Aromatic polyesters, for instance, may be obtained from (1) two or morearomatic hydroxycarboxylic acids; (2) at least one aromatichydroxycarboxylic acid, at least one aromatic dicarboxylic acid, and atleast one aromatic diol; and/or (3) at least one aromatic dicarboxylicacid and at least one aromatic diol. Examples of suitable aromatichydroxycarboxylic acids include, 4-hydroxybenzoic acid;4-hydroxy-4′-biphenylcarboxylic acid; 2-hydroxy-6-naphthoic acid;2-hydroxy-5-naphthoic acid; 3-hydroxy-2-naphthoic acid;2-hydroxy-3-naphthoic acid; 4′-hydroxyphenyl-4-benzoic acid;3′-hydroxyphenyl-4-benzoic acid; 4′-hydroxyphenyl-3-benzoic acid, etc.,as well as alkyl, alkoxy, aryl and halogen substituents thereof.Examples of suitable aromatic dicarboxylic acids include terephthalicacid; isophthalic acid; 2,6-naphthalenedicarboxylic acid; diphenylether-4,4′-dicarboxylic acid; 1,6-naphthalenedicarboxylic acid;2,7-naphthalenedicarboxylic acid; 4,4′-dicarboxybiphenyl;bis(4-carboxyphenyl)ether; bis(4-carboxyphenyl)butane;bis(4-carboxyphenyl)ethane; bis(3-carboxyphenyl)ether;bis(3-carboxyphenyl)ethane, etc., as well as alkyl, alkoxy, aryl andhalogen substituents thereof. Examples of suitable aromatic diolsinclude hydroquinone; resorcinol; 2,6-dihydroxynaphthalene;2,7-dihydroxynaphthalene; 1,6-dihydroxynaphthalene;4,4′-dihydroxybiphenyl; 3,3′-dihydroxybiphenyl; 3,4′-dihydroxybiphenyl;4,4′-dihydroxybiphenyl ether; bis(4-hydroxyphenyl)ethane, etc., as wellas alkyl, alkoxy, aryl and halogen substituents thereof. In oneparticular embodiment, the aromatic polyester is derived from4-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid. The monomer unitsderived from 4-hydroxybenzoic acid may constitute from about 45% toabout 85% (e.g., 73%) of the polymer on a mole basis and the monomerunits derived from 2,6-hydroxynaphthoic acid may constitute from about15% to about 55% (e.g., 27%) of the polymer on a mole basis. Thesynthesis and structure of these and other aromatic polyesters may bedescribed in more detail in U.S. Pat. Nos. 4,161,470; 4,473,682;4,522,974; 4,375,530; 4,318,841; 4,256,624; 4,219,461; 4,083,829;4,184,996; 4,279,803; 4,337,190; 4,355,134; 4,429,105; 4,393,191;4,421,908; 4,434,262; and 5,541,240.

Liquid crystalline polyesteramides may likewise be obtained from (1) atleast one aromatic hydroxycarboxylic acid and at least one aromaticaminocarboxylic acid; (2) at least one aromatic hydroxycarboxylic acid,at least one aromatic dicarboxylic acid, and at least one aromatic amineand/or diamine optionally having phenolic hydroxy groups; and (3) atleast one aromatic dicarboxylic acid and at least one aromatic amineand/or diamine optionally having phenolic hydroxy groups. Suitablearomatic amines and diamines may include, for instance, 3-aminophenol;4-aminophenol; 1,4-phenylenediamine; 1,3-phenylenediamine, etc., as wellas alkyl, alkoxy, aryl and halogen substituents thereof. In oneparticular embodiment, the aromatic polyesteramide is derived from2,6-hydroxynaphthoic acid, terephthalic acid, and 4-aminophenol. Themonomer units derived from 2,6-hydroxynaphthoic acid may constitute fromabout 35% to about 85% of the polymer on a mole basis (e.g., 60%), themonomer units derived from terephthalic acid may constitute from about5% to about 50% (e.g., 20%) of the polymer on a mole basis, and themonomer units derived from 4-aminophenol may constitute from about 5% toabout 50% (e.g., 20%) of the polymer on a mole basis. In anotherembodiment, the aromatic polyesteramide contains monomer units derivedfrom 2,6-hydroxynaphthoic acid, and 4-hydroxybenzoic acid, and4-aminophenol, as well as other optional monomers (e.g.,4,4′-dihydroxybiphenyl and/or terephthalic acid). The synthesis andstructure of these and other aromatic poly(esteramides) may be describedin more detail in U.S. Pat. Nos. 4,339,375; 4,355,132; 4,351,917;4,330,457; 4,351,918; and 5,204,443.

Meanwhile, the term “aramid polymer” refers to a class of polymers knownas aromatic polyamides. Such polymers are typically prepared by thereaction between an amine group and a carboxylic acid halide group.Examples of suitable aramid polymers contemplated by the presentinvention include poly-metaphenylene isophthalam ides and p-phenyleneterephthalam ides.

However, in order to achieve the desired abrasion resistance, it is tobe understood that the additional polymer should be present in an amountof less than about 5 wt. % of the total weight of the sheath 104, suchas in an amount of less than about 2.5 wt. % of the total weight of thesheath 104, such as in an amount of less than about 1 wt. % of the totalweight of the sheath 104.

III. Applications

The braided structure of the present invention can be utilized invarious medical applications. For instance, in some embodiments, thebraided structure can be utilized as a suture material. Further, inother embodiments, the braided structure can be used as an actuationcable for a medical device. In addition, the braided structure can beused for any other application as known to one of skill in the art. Forexample, the braided structure can be used in load bearing orthopedicapplications, artificial tendons/ligaments, device fixation, actuationcables, components for tissue repair, etc.

The present invention may be better understood by reference to thefollowing example.

EXAMPLE

Several braided structures were formed as shown below in Table 1,included comparative examples C1a-C17 and examples 1a-4 and S1-S5, andthe braided structures exhibited the physical and mechanical propertiessummarized in Table 1. Details as to the specific test proceduresutilized to determine each property are set forth below.

Test Procedures

-   -   1. Sheath yarn twists per inch (TPI) was determined by using the        direct untwist method on a hand driven twist tester    -   2. Braid diameter was determined by using a laser micrometer        while a 30 gram weight was applied to the braided structure    -   3. Picks per inch (PPI) was determined by using an electronic        measurement system while the braided structure was under        magnification    -   4. Break load was determined by measuring the tensile force at        which the braided structure failed using a universal mechanical        testing system, with the tensile force being applied in the        axial direction    -   5. Break load with 180° bend was determined by measuring the        tensile force at which the braided structure failed while bent        at 180° over a wire or pin having a diameter of 0.012 inches        using a universal mechanical testing system    -   6. Ultimate tensile strength (UTS) was determined according to        the following formula:

UTS=Break Load/(3.14×(radius of braided structure)²)

-   -   7. Extension at Break was determined calculating the percent        elongation of the braided structure at the point of failure        using a universal mechanical testing system    -   8. Stiffness was determined according to the following formula:

Stiffness=Break Load/Extension at Break

-   -   9. Creep was calculated by determining the amount of elongation        and percent of elongation of the braided structure. The braided        structure was lopped around itself where both braid ends are        parallel to one another in one testing grip to create a double        braided structure. Using this double braided structure at a        constant 5 pounds-force (about 22.2 Newtons) for about 15        minutes and at an about 19 inch (48.3 centimeter) gage length on        a horn grip, then normalizing this value by multiplying the        elongation of the braided structure at about 15 minutes by a set        ratio longer than the test gage length vs. the test gage length    -   10. Abrasion resistance rankings of excellent, adequate, or poor        were obtained based on the following: each sample braided        structure was cycled 20 millimeters in a backwards direction and        20 millimeters in a forwards direction for a total of 40 cycles        across a metal edge having a 1 millimeter radius with 200 grams        of weight applied to the braided structure and the number of        broken filaments in an inch of the braid was determined, where a        ranking of excellent was given for braided structures with less        than 10 broken filaments, a ranking of adequate was given for        braided structures with between 10 and 50 broken filaments, and        a ranking of poor was given for braided structures with more        than 50 broken filaments

TABLE 1 Picks Break Core Yarn Diameter Per Load Sample Sheath YarnDescription Description (Inches) Inch (Ibf) C1a 50D LCP^(A), 12 TPI S &Z 100D LCP TS^(H) 0.0104 28 19.15 C1b 50D LCP^(A), 12 TPI S & Z 100D LCPTS^(H) 0.0104 20 20.77 C1c 50D LCP^(A), 12 TPI S & Z 100D LCP TS^(H)0.0104 38 15.46 C2a 50D LCP^(A), 12 TPI S & Z 100D UHMWPE^(J) 0.0110 2820.27 C2b 50D LCP^(A), 12 TPI S & Z 100D UHMWPE^(J) 0.0110 20 22.34 C2c50D LCP^(A), 12 TPI S & Z 100D UHMWPE^(J) 0.0110 38 15.74 C3 50DLCP^(A), 12 TPI S & Z 100D UHMWPE^(K) 0.0100 28 19.51 C4 50D UHMWPE^(B),3 TPI S & Z 100D LCP^(H) 0.0115 20 23.44 C5 50D UHMWPE^(B), 3 TPI S & Z50D UHMWPE^(L) 0.0117 25 23.58 C6 50D LCP^(C) Untwisted 100D LCP^(H)0.0100 20 28.86 C7 50D LCP^(D), 6.5 TPI S & Z 100D LCP^(H) 0.0107 2021.83 C8 50D UHMWPE^(E), 6.5 TPI S & Z 100D LCP^(H) 0.0118 20 25.36 C950D UHMWPE^(E), 6.5 TPI S & Z 100D LCP^(H) 0.0118 14 27.47 C10 50DLCP^(C) Untwisted 100D LCP^(H) 0.0099 14 28.82 C11 30D UHMWPEUntwisted^(M) 600D Aramid 0.0144 88 12.43 C12 30D UHMWPE Untwisted^(M)800D Aramid 0.0159 88 16.37 C13 30D UHMWPE Untwisted^(M) 600D Aramid0.0147 36 40.04 C14 30D UHMWPE Untwisted^(M) 600D Aramid 0.0147 46 34.62C15 30D UHMWPE Untwisted^(M) 600D Aramid 0.0147 — 21.13 C16 30D UHMWPEUntwisted^(M) 400 D Aramid, 5 TPI 0.0125 65 28.26 C17 40DPolyethyleneTerephthalate 400D Aramid, 5 TPI 0.0126 54 22.65Untwisted^(N) 1a 50D UHMWPE^(E), 6.5 TPI S & Z 100D LCP^(I) 0.0116 2018.25 1b 50D UHMWPE^(E), 6.5 TPI S & Z 100D LCP^(I) 0.0116 28 18.38 1c50D UHMWPE^(E), 6.5 TPI S & Z 100D LCP^(I) 0.0116 38 19.55 2 50DUHMWPE^(E), 6.5 TPI S & Z 100D LCP^(I) 0.0119 14 20.17 3 50DUHMWPE^(F), 6.5 TPI S & Z 100D LCP^(I) 0.0117 20 22.23 4 50D UHMWPE^(G),6.5 TPI S & Z 100D LCP^(I) 0.0116 20 26.19 S1 30D UHMWPE Untwisted^(M)25D LCP^(P) 0.0082 20 14.77 S2 30D UHMWPE Untwisted^(M) 25D LCP^(P)0.0229 20 52.15 S3 30D UHMWPE Untwisted^(M) 25D LCP^(P) 0.0076 20 9.62S4 100D UHMWPE Untwisted^(O) 25D LCP^(P) 0.0142 20 32.15 S5 50DUHMWPE^(E), 6.5 TPI S & Z 25D LCP^(P) 0.0110 20 21.50 Break UltimateLoad Tensile (lbf) Extension Strength 180° at Break Stiffness CreepCreep Abrasion Sample (psi) Bend (%) (lbf/in.) (Inches) (% extension)Resistance C1a 2.26.E+05 17.16 3.2% 37.32 0.028 0.15% Poor C1b 2.45.E+0517.75 — — — — Poor C1c 1.82.E+05 18.89 — — — — Poor C2a 2.13.E+05 17.793.2% 39.20 0.039 0.21% Poor C2b 2.35.E+05 21.92 — — — — Poor C2c1.66.E+05 18.81 — — — — Poor C3 2.48.E+05 — 3.0% 40.64 0.030 0.16% PoorC4 2.26.E+05 — 6.8% 21.87 0.090 0.47% Excellent C5 2.19.E+05 — 5.2%27.30 0.074 0.39% Excellent C6 3.68.E+05 — 3.8% 46.33 0.215 1.13% PoorC7 2.43.E+05 — 3.6% 37.65 0.127 0.67% Poor C8 2.32.E+05 26.54 6.0% 27.370.314 1.65% Excellent C9 2.51.E+05 28.26 5.8% 28.71 0.276 1.45%Excellent C10 3.75.E+05 — 3.6% 48.68 0.190 1.00% Poor C11 7.64.E+0418.13 2.1 49.77 0.084 0.44% Adequate C12 8.25.E+04 28.21 2.1 63.92 0.0460.24% Excellent C13 2.36.E+05 — 5.6 59.26 — — — C14 2.04.E+05 — 5.158.00 — — — C15 1.25.E+05 — 2.9 62.34 — — — C16 2.30.E+05 — 4.5 52.72 —— — C17 1.82.E+05 23.76 3.8 49.19 0.046 0.24% Poor 1a 1.73.E+05 18.634.1% 27.52 0.230 1.21% Excellent 1b 1.74.E+05 18.01 — — — — Excellent 1c1.85.E+05 24.73 — — — — Excellent 2 1.81.E+05 24.26 3.8% 32.36 0.2391.26% Excellent 3 2.07.E+05 — 2.3% 58.95 0.164 0.86% Excellent 42.48.E+05 — 2.6% 63.55 0.134 0.71% Excellent S1 2.80.E+05 19.98 3.7%27.75 0.470 2.47% Excellent S2 1.27.E+05 61.55 4.2% 85.07 0.271 1.43%Excellent S3 2.12.E+05 15.07 3.2% 20.72 0.542 2.85% Excellent S42.03.E+05 34.73 3.6% 60.82 0.261 1.37% Excellent S5 2.26.E+05 24.74 3.3%34.93 0.335 1.76% Excellent

Explanation of Superscripts in Sheath Yarn Description and Core YarnDescription Columns:

-   A—45-55 denier; 24 filaments; 0.002467-0.002934 inch diameter;    2.3-3.1% elongation; 22-33 tenacity (g/denier); 990-1815 g max    force; 11-13 TPI-   B—45-56 denier; 25 filaments; 0.003188-0.003557 inch diameter; 2-7%    elongation; 22-47 tenacity (g/denier); 990-2632 g max force; 1-5 TPI-   C—47-55 denier; 24 filaments; 0.002521-0.002934 inch diameter;    3-4.5% elongation; 21.5-38.4 tenacity (g/denier); 1010.5-2113.1 g    max force; 0 TPI-   D—45-55 denier; 24 filaments; 0.002521-0.002934 inch diameter; 3-5%    elongation; 20-40 tenacity (g/denier); 900-2200 g max force; 5-9 TPI-   E—46-56 denier; 25 filaments; 0.003224-0.003557 inch diameter; 2-7%    elongation; 25-45 tenacity (g/denier); 1150-2520 g max force; 5-9    TPI-   F—46-57 denier; 20 filaments; 0.003224-0.003588 inch diameter;    1.9-4.7% elongation; 28-48 tenacity (g/denier); 1288-2736 g max    force; 5-9 TPI-   G—40-60 denier; 31-35 filaments; 0.003006-0.003682 inch diameter;    1.3-5% elongation; 37.4-50.6 tenacity (g/denier); 1496-3036 g max    force; 5-9 TPI-   H—94-105 denier; 48 filaments; 0.003566-0.004054 inch diamater;    2.5-4.5% elongation; 22-36 tenacity (g/denier); 2068-3780 g max    force; 0 TPI-   I—96-105 denier; 48 filaments; 0.003604-0.004054 inch diameter;    2.1-2.5% elongation; 21-28 tenacity (g/denier); 2016-2940 g max    force; 0 TPI-   J—90-110 denier; 40-48 filaments; 0.004509-0.004985 inch diameter;    2.1-4.5% elongation; 28.5-41.2 tenacity (g/denier); 2565.9-4535.3 g    max force; 0 TPI-   K—92-114 denier; 40 filaments; 0.004559-0.005075 inch diameter;    1.9-4.7% elongation; 28-48 tenacity (g/denier); 2576-5472 g max    force; 0 TPI-   L—45-56 denier; 25 filaments; 0.003188-0.003557 inch diameter;    2.3-4.5% elongation; 28-40 tenacity (g/denier); 1260-2240 g max    force; 0 TPI-   M—25-35 denier; 16 filaments; 0.00303-0.00403 inch diameter; 2-5%    elongation; 20-55 tenacity (g/denier); 650-1700 g max force; 0 TPI-   N—35-45 denier; 27 filaments; 0.002357-0.002673 inch diameter;    19-45% elongation; 3.8-5.2 tenacity (g/denier); 130-235 g max force,    0 TPI-   O—80-120 denier; 41 filaments; 0.004251-0.00520658 inch diameter;    2.5-4.5% elongation; 25-45 tenacity (g/denier); 2500-4500 g max    force; 0 TPI-   P—21-29 denier; 6 filaments; 0.001839-0.00220275 inch diameter; 3-5%    elongation; 20-40 tenacity (g/denier); 600-950 g max force

Discussion

As shown above in Table 1, which summarizes the various braidedstructures and their resulting physical and mechanical properties,although comparative samples C1 through C17 had the small diameterrequired for the braided structure for use in medical applications, noneof the comparative samples C1 through C17 exhibited the most preferredmechanical properties across all categories. For instance, comparativesamples C4, C8, C9, and C13 exhibited high extension at breakpercentages, C11 and C12 exhibited low ultimate tensile strengths, andsamples C1a, C1b, C1c, C2a, C2b, C2c, C3, C6, C7, C10, C11, and C17exhibited poor abrasion resistance as evidenced by fraying of thebraided structure after cycling the braided structure 20 millimeters ina backwards direction and 20 millimeters in a forwards direction for atotal of 40 cycles across a metal edge having a 1 millimeter radius with200 grams of weight applied to the braided structure.

On the other hand, surprisingly, the specific arrangement of the braidedstructures of samples 1a, 1b, 1c, 2, 3, and 4 and samples S1, S2, S3,S4, and S5 were abrasion resistant, exhibited high loads at break in thenormal and 180° bend testing configurations, exhibited low extension atbreak, exhibited increased stiffness, and had low creep values, allwhile having a small diameter suitable for use in suture or actuationcable applications and maintaining a high ultimate tensile strengthranging from 1.27×10⁵ pounds per square inch (about 876 megapascals) to2.80×10⁵ pounds per square inch (about 1930 megapascals). In anotheraspect, the braided structure can exhibit an ultimate tensile strengthranging from about 15 grams/denier yarn to about 35 grams/denier yarn.

FIGS. 3-10 will now be discussed in more detail to demonstrate theimproved abrasion resistance of the braided structure of the presentinvention compared to other braided structures. Specifically, FIG. 3 isa photograph of a braided structure having a liquid crystalline polymersheath as in comparative examples C1a-C3, C6-C7, and C10 after cyclingthe braided structure 20 millimeters in a backwards direction and 20millimeters in a forwards direction for a total of 5 cycles across ametal edge having a 1 millimeter radius with 200 grams of weight appliedto the braided structure; FIG. 4 is a photograph of a braided structurehaving a liquid crystalline polymer sheath as in comparative examplesC1a-C3, C6-C7, and C10 after cycling the braided structure 20millimeters in a backwards direction and 20 millimeters in a forwardsdirection for a total of 10 cycles across a metal edge having a 1millimeter radius with 200 grams of weight applied to the braidedstructure; FIG. 5 is a photograph of a braided structure having a liquidcrystalline polymer sheath as in comparative examples C1a-C3, C6-C7, andC10 after cycling the braided structure 20 millimeters in a backwardsdirection and 20 millimeters in a forwards direction for a total of 20cycles across a metal edge having a 1 millimeter radius with 200 gramsof weight applied to the braided structure; and FIG. 6 is a photographof a braided structure having a liquid crystalline polymer sheath as incomparative examples C1a-C3, C6-C7, and C10 after cycling the braidedstructure 20 millimeters in a backwards direction and 20 millimeters ina forwards direction for a total of 40 cycles across a metal edge havinga 1 millimeter radius with 200 grams of weight applied to the braidedstructure. As shown, even after only 5 cycles, the braided structure asin comparative examples C1a-C3, C6-C7, and C10 exhibits fraying, whichis even far more pronounced after 40 cycles, indicating that the braidedstructures of comparative examples C1a-C3, C6-C7, and C10 lack abrasionresistance.

On the other hand, FIG. 7 is a photograph of a braided structure havingan ultra high molecular weight polyethylene polymer sheath as inexamples 1a-4 and S1-S5 after cycling the braided structure 20millimeters in a backwards direction and 20 millimeters in a forwardsdirection for a total of 5 cycles across a metal edge having a 1millimeter radius with 200 grams of weight applied to the braidedstructure; FIG. 8 is a photograph of a braided structure having an ultrahigh molecular weight polyethylene polymer sheath as in examples 1a-4and S1-S5 after cycling the braided structure 20 millimeters in abackwards direction and 20 millimeters in a forwards direction for atotal of 10 cycles across a metal edge having a 1 millimeter radius with200 grams of weight applied to the braided structure; FIG. 9 is aphotograph of a braided structure having an ultra high molecular weightpolyethylene polymer sheath as in examples 1a-4 and S1-S5 after cyclingthe braided structure 20 millimeters in a backwards direction and 20millimeters in a forwards direction for a total of 20 cycles across ametal edge having a 1 millimeter radius with 200 grams of weight appliedto the braided structure; and FIG. 10 is a photograph of a braidedstructure having an ultra high molecular weight polyethylene polymersheath as in examples 1a-4 and S1-S5 after cycling the braided structure20 millimeters in a backwards direction and 20 millimeters in a forwardsdirection for a total of 40 cycles across a metal edge having a 1millimeter radius with 200 grams of weight applied to the braidedstructure. As shown, even after 40 cycles, the braided structures as inexamples 1a-4 and S1-S5 show no fraying, indicating the braidedstructures of the present invention are abrasion resistant.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A braided structure comprising: a core comprisingat least one yarn, wherein the yarn comprises an aromatic polymer; and asheath braided around the core, wherein the sheath comprises a pluralityof ultra-high molecular weight polyolefin yarns, wherein the braidedstructure has an overall diameter ranging from about 60 micrometers toabout 650 micrometers.
 2. The braided structure of claim 1, wherein thearomatic polymer comprises a liquid crystalline polymer, an aramidpolymer, or a combination thereof.
 3. The braided structure of claim 1,wherein the sheath comprises from 2 yarns to about 48 yarns and each ofthe plurality of yarns in the sheath comprises from 1 filament to about72 filaments.
 4. The braided structure of claim 1, wherein the sheathcomprises at least two sheath layers.
 5. The braided structure of claim1, wherein the yarn comprises from about 3 filaments to about 96filaments.
 6. The braided structure of claim 1, wherein the ultra-highmolecular weight polyolefin comprises an ultrahigh molecular weightpolyethylene having a weight average molecular weight (Mw) of at leastabout 500,000 grams/mole (g/mol).
 7. The braided structure of claim 1,wherein the braided structure exhibits a creep of less than 8 percentelongation after about 15 minutes.
 8. The braided structure of claim 1,wherein the braided structure exhibits resistance to abrasion aftercycling the braided structure 20 millimeters in a backwards directionand 20 millimeters in a forwards direction for a total of 40 cyclesacross a metal edge having a 1 millimeter radius with 200 grams ofweight applied to the braided structure, wherein the braided structureincludes less than 50 broken filaments per linear inch after cycling. 9.The braided structure of claim 1, wherein the braided structure exhibitsa load at break ranging from about 5 pounds-force (about 22.2 Newtons)to about 60 pounds-force (about 266.9 Newtons).
 10. The braidedstructure of claim 1, wherein the braided structure exhibits anextension at break ranging from about 2% to about 5.5%.
 11. The braidedstructure of claim 1, wherein the braided structure exhibits a stiffnessranging from about 10 pounds-force per inch (about 1.75Newtons/millimeter) to about 90 pounds-force per inch (about 15.8Newtons/millimeter).
 12. The braided structure of claim 1, wherein thebraided structure exhibits an ultimate tensile strength ranging fromabout 8.0×10⁴ pounds per square inch (about 550 megapascals) to about3.9×10⁵ pounds per square inch (about 2710 megapascals).
 13. The braidedstructure of claim 1, wherein the braided structure comprises from about10 picks per inch (PPI) to about 90 picks per inch (PPI).
 14. Thebraided structure of claim 1, wherein the sheath yarn comprises from 0twists per inch (TPI) to about 12 twists per inch (TPI).
 15. The braidedstructure of claim 1, wherein the core yarn comprises zero twists perinch (TPI) to about 2 twists per inch (TPI).
 16. The braided structureof claim 1, wherein each of the plurality of yarns in the sheath has alinear mass density ranging from about 8 denier to about 125 denier. 17.The braided structure of claim 1, wherein the yarn in the core has alinear mass density ranging from about 8 denier to about 1110 denier.18. An actuation cable for a medical device, a suture, a load bearingorthopedic application, an artificial tendon or ligament, a componentfor tissue repair, and actuation cable, or a fixation device comprisingthe braided structure of claim
 1. 19. A braided structure comprising: acore comprising at least one yarn, wherein the yarn comprises anaromatic polymer; and a sheath braided around the core, wherein thesheath comprises a plurality of ultra-high molecular weight polyolefinyarns, wherein the braided structure exhibits resistance to abrasionafter cycling the braided structure 20 millimeters in a backwardsdirection and 20 millimeters in a forwards direction for a total of 40cycles across a metal edge having a 1 millimeter radius with 200 gramsof weight applied to the braided structure, wherein the braidedstructure includes less than 50 broken filaments per linear inch aftercycling.
 20. A braided structure comprising: a core comprising at leastone yarn, wherein the yarn comprises an aromatic polymer; and a sheathbraided around the core, wherein the sheath comprises a plurality ofultra-high molecular weight polyolefin yarns, wherein the braidedstructure exhibits a creep of less than about 8 percent elongation afterabout 15 minutes.